Stefan Kangas <stefankangas@gmail.com> writes:

> My measurements show that 32 KiB might be a good choice, and gives a
> ~95% speedup:
>
> | Chunk size (KiB) | Completion time (s) |
> |------------------+---------------------|
> |                4 |                29.3 |
> |                8 |                18.2 |
> |               16 |                12.7 |
> |               32 |                 7.4 |
> |               64 |                 6.5 |
> |              128 |                 5.4 |

BTW, to reproduce these measurements, try the attached.